The treasure trove of 91,000 classified AfPak documents posted by WikiLeaks suggests that our government’s been deceiving us about Pakistan’s murderous behavior.

But the situation’s even worse than that: Our government’s been lying to itself.

The documents in question aren’t superclassified. They’re largely low-level field reports at the “confidential” level, bottom-rung stuff, with some secret documents mixed in. Their value lies in their unfiltered quality. This is what the guys on the ground with the guns have been seeing, hearing and sensing.

It ain’t good. Reports covering the five years from 2004 to 2009 cite routine Pakistani support for the Afghan Taliban — as the terrorists kill our troops. Pakistan’s infamous Inter Services Intelligence, or ISI, also has been working with al Qaeda, according to the reports.

That’s no surprise to Post readers, but our government is “shocked, shocked!” by the revelations. And the excuses for Pakistan’s lethal misconduct have already started flowing.

We’re told that these reports are unverified, that some can be traced back to anti-Pakistani Afghan intelligence operatives, and that American eyewitness accounts are one-offs.

Folks, I’ve done plenty of intelligence analysis, and here’s how it works: A single report of a supposed ally’s wrongdoing gets your attention, but it’s regarded as an outlier until another source confirms it. After that, you actively search for further corroboration — before you get blindsided big time.

One report might be hearsay. But hundreds of reports of Pakistani collaboration with our Taliban and al Qaeda enemies amount to a pattern. And intelligence is about patterns.

Our government’s response to Pakistani complicity in the death of hundreds of our troops and the wounding of thousands? Send additional aid — on top of the $6 billion recently committed — and bills in Congress to grant special trade privileges to Pakistanis in Taliban-infested territories.

It’s like dating someone who’s wildly, flagrantly promiscuous and hoping that patience will lead to his or her sudden reform. But tolerance only encourages more bad behavior.

Gen. David Petraeus, our new commander in Afghanistan, knows that the Pakistanis are corrupt and deceitful. But he, too, continues to hope they’ll see the light.

Why do Petraeus and other veteran officials continue to dream of Pakistan’s magical self-reformation? Because we’re out of strategic imagination, having tied ourselves to Pakistan for everything from the transit of supplies for our troops to intelligence.

We’re begging the Pakistanis to make fools of us. Our troops die — and we make excuses for their killers.

Of course, this shouldn’t be too great a surprise, given that our government insists that Islamist terrorists have nothing to do with Islam and that jihad’s just a peaceful inner struggle. (Check out al Qaeda’s new online magazine if you want a little taste of Islamist pacifism.)

Then there’s the other issue: How did a lowest-of-the-low-level player provide WikiLeaks with 92,000 classified documents, even if they weren’t “highly” classified?

It was easy. Millions of soldiers, officials and contractors have access to confidential and secret-level material (only seven or eight hundred thousand have top-secret clearances, so I guess that’s safe . . .). Many firewalls are a joke to keyboard jockeys. The real surprise in the Internet age is that we haven’t seen more massive leaks of far more sensitive documents.

A disgruntled soldier, a bureaucrat who didn’t get a promotion or a contractor given his walking papers could do massive damage in his last hour on the job.

And there are no serious penalties. Leaking classified info won’t get you into much hot water when even spying just lands you a plane ticket home, a photo op and a book deal.

It would be helpful if this latest security breakdown at least provoked our government to get a teensy bit serious about cyber-security and the culture of leaks. But don’t hold your breath. Pakistan will hand over Mullah Omar and Osama bin Laden before our government takes its own laws seriously.